What primarily drew me to Kazurei as a pairing isn't the roommate trope, nor the golden retriever and brood cat trope, or the gay spy x family gag, but rather this scene from Episode 8 (that I'm somehow still not over.)

It's the mutual reluctance to love and let themselves heal, with the exception that Kazuki couldn't stand to see Rei in the same position as him, so he offers to take care of him anyway. Both, who had a rough relationship with love, let themselves confide in each other. Rei, who found comfort and experienced what it's like to be taken care of, and Kazuki, who can't help but to extend care because it's something that's just... natural to do in his position. Kazuki, who is hurted by love that is taken from him over and over again, offers what he'd regard as a bare minimum because deep down, he wants his remaining loved ones (and in this timeline just rei) to feel the love he always desired.

Though Kazuki is seemingly full of emotions every time (enough to almost repress his sadness), his actions are always so gentle and full of warmth.

What makes it more beautiful is how Rei adapts Kazuki concept's, or rather, way to express love to Miri (with the most apparent example being Episode 9) considering Kazuki was probably one of if not the first person he'd experienced and therefore actively saw it from. He initially wasn't able to comprehend how to love and be loved, and only through Kazuki's deeds did he learn how comforting and nice it is to be cared for, so he wanted to extend that to Miri after realizing how much his family meant to him.

Going back to the topic, I genuinely adore how Kazurei is a pairing consisting of two people who weren't given the opportunity to love, and during their time before Miri subconsciously fulfilled each other's emotional needs. Though initially distant, they immediately clicked because they fit together like puzzle pieces. Similar desires but difference in approach and seek what the other has.

While there is mutual understanding between them, being able to read each other, neither of the two had the will to step onto each others' boundaries and address it. It was satisfying to see them grow closer emotionally and form the courage to communicate, with great examples being the last few episodes of the series.

Tl;dr the soft aspect of Kazurei made me complerely fall in love with the pairing and I used to be neutral about it